[core] Move comment to PROGMEM on ESP8266

esphome/components/web_server/web_server.cpp

@@ -287,7 +287,9 @@ std::string WebServer::get_config_json() {
   JsonObject root = builder.root();
 
   root[ESPHOME_F("title")] = App.get_friendly_name().empty() ? App.get_name() : App.get_friendly_name();
-  root[ESPHOME_F("comment")] = App.get_comment_ref();
+  char comment_buffer[ESPHOME_COMMENT_SIZE];
+  App.get_comment_string(comment_buffer, sizeof(comment_buffer));
+  root[ESPHOME_F("comment")] = comment_buffer;
 #if defined(USE_WEBSERVER_OTA_DISABLED) || !defined(USE_WEBSERVER_OTA)
   root[ESPHOME_F("ota")] = false;  // Note: USE_WEBSERVER_OTA_DISABLED only affects web_server, not captive_portal
 #else

esphome/core/application.h

@@ -12,6 +12,7 @@
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/preferences.h"
+#include "esphome/core/progmem.h"
 #include "esphome/core/scheduler.h"
 #include "esphome/core/string_ref.h"
 #include "esphome/core/version.h"
@@ -104,8 +105,7 @@ static const uint32_t TEARDOWN_TIMEOUT_REBOOT_MS = 1000;  // 1 second for quick
 
 class Application {
  public:
-  void pre_setup(const std::string &name, const std::string &friendly_name, const char *comment,
-                 bool name_add_mac_suffix) {
+  void pre_setup(const std::string &name, const std::string &friendly_name, bool name_add_mac_suffix) {
     arch_init();
     this->name_add_mac_suffix_ = name_add_mac_suffix;
     if (name_add_mac_suffix) {
@@ -124,7 +124,6 @@ class Application {
       this->name_ = name;
       this->friendly_name_ = friendly_name;
     }
-    this->comment_ = comment;
   }
 
 #ifdef USE_DEVICES
@@ -257,10 +256,21 @@ class Application {
     return "";
   }
 
-  /// Get the comment of this Application set by pre_setup().
-  std::string get_comment() const { return this->comment_; }
-  /// Get the comment as StringRef (avoids allocation)
-  StringRef get_comment_ref() const { return StringRef(this->comment_); }
+  /// Copy the comment string into the provided buffer
+  /// Buffer must be ESPHOME_COMMENT_SIZE bytes
+  void get_comment_string(char *buffer, size_t size) {
+    ESPHOME_strncpy_P(buffer, ESPHOME_COMMENT_STR, size);
+    buffer[size - 1] = '\0';
+  }
+
+  /// Get the comment of this Application (deprecated, use get_comment_string() instead)
+  // Remove before 2026.7.0
+  ESPDEPRECATED("Use get_comment_string() instead. Removed in 2026.7.0", "2026.1.0")
+  std::string get_comment() {
+    char buffer[ESPHOME_COMMENT_SIZE];
+    this->get_comment_string(buffer, sizeof(buffer));
+    return std::string(buffer);
+  }
 
   bool is_name_add_mac_suffix_enabled() const { return this->name_add_mac_suffix_; }
 
@@ -501,7 +511,6 @@ class Application {
 
   // Pointer-sized members first
   Component *current_component_{nullptr};
-  const char *comment_{nullptr};
 
   // std::vector (3 pointers each: begin, end, capacity)
   // Partitioned vector design for looping components

esphome/core/build_info_data.h

@@ -7,4 +7,6 @@
 
 #define ESPHOME_CONFIG_HASH 0x12345678U  // NOLINT
 #define ESPHOME_BUILD_TIME 1700000000    // NOLINT
+#define ESPHOME_COMMENT_SIZE 1           // NOLINT
 static const char ESPHOME_BUILD_TIME_STR[] = "2024-01-01 00:00:00 +0000";
+static const char ESPHOME_COMMENT_STR[] = "";

esphome/core/config.py

@@ -209,7 +209,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Required(CONF_NAME): cv.valid_name,
             cv.Optional(CONF_FRIENDLY_NAME, ""): cv.All(cv.string, cv.Length(max=120)),
             cv.Optional(CONF_AREA): validate_area_config,
-            cv.Optional(CONF_COMMENT): cv.string,
+            cv.Optional(CONF_COMMENT): cv.All(cv.string, cv.Length(max=255)),
             cv.Required(CONF_BUILD_PATH): cv.string,
             cv.Optional(CONF_PLATFORMIO_OPTIONS, default={}): cv.Schema(
                 {
@@ -505,7 +505,6 @@ async def to_code(config: ConfigType) -> None:
         cg.App.pre_setup(
             config[CONF_NAME],
             config[CONF_FRIENDLY_NAME],
-            config.get(CONF_COMMENT, ""),
             config[CONF_NAME_ADD_MAC_SUFFIX],
         )
     )

esphome/writer.py

@@ -271,7 +271,7 @@ def copy_src_tree():
         "esphome", "core", "build_info_data.h"
     )
     build_info_json_path = CORE.relative_build_path("build_info.json")
-    config_hash, build_time, build_time_str = get_build_info()
+    config_hash, build_time, build_time_str, comment = get_build_info()
 
     # Defensively force a rebuild if the build_info files don't exist, or if
     # there was a config change which didn't actually cause a source change
@@ -292,7 +292,9 @@ def copy_src_tree():
     if sources_changed:
         write_file(
             build_info_data_h_path,
-            generate_build_info_data_h(config_hash, build_time, build_time_str),
+            generate_build_info_data_h(
+                config_hash, build_time, build_time_str, comment
+            ),
         )
         write_file(
             build_info_json_path,
@@ -332,31 +334,43 @@ def generate_version_h():
     )
 
 
-def get_build_info() -> tuple[int, int, str]:
+def get_build_info() -> tuple[int, int, str, str]:
     """Calculate build_info values from current config.
 
     Returns:
-        Tuple of (config_hash, build_time, build_time_str)
+        Tuple of (config_hash, build_time, build_time_str, comment)
     """
     config_hash = CORE.config_hash
     build_time = int(time.time())
     build_time_str = time.strftime("%Y-%m-%d %H:%M:%S %z", time.localtime(build_time))
-    return config_hash, build_time, build_time_str
+    comment = CORE.comment or ""
+    return config_hash, build_time, build_time_str, comment
+
+
+def _escape_c_string(s: str) -> str:
+    """Escape a string for use in a C string literal."""
+    return s.replace("\\", "\\\\").replace('"', '\\"').replace("\n", "\\n")
 
 
 def generate_build_info_data_h(
-    config_hash: int, build_time: int, build_time_str: str
+    config_hash: int, build_time: int, build_time_str: str, comment: str
 ) -> str:
-    """Generate build_info_data.h header with config hash and build time."""
+    """Generate build_info_data.h header with config hash, build time, and comment."""
+    escaped_comment = _escape_c_string(comment)
+    # +1 for null terminator
+    comment_size = len(comment) + 1
     return f"""#pragma once
 // Auto-generated build_info data
 #define ESPHOME_CONFIG_HASH 0x{config_hash:08x}U  // NOLINT
 #define ESPHOME_BUILD_TIME {build_time}  // NOLINT
+#define ESPHOME_COMMENT_SIZE {comment_size}  // NOLINT
 #ifdef USE_ESP8266
 #include <pgmspace.h>
 static const char ESPHOME_BUILD_TIME_STR[] PROGMEM = "{build_time_str}";
+static const char ESPHOME_COMMENT_STR[] PROGMEM = "{escaped_comment}";
 #else
 static const char ESPHOME_BUILD_TIME_STR[] = "{build_time_str}";
+static const char ESPHOME_COMMENT_STR[] = "{escaped_comment}";
 #endif
 """
 

tests/unit_tests/test_writer.py

@@ -1357,36 +1357,67 @@ def test_generate_build_info_data_h_format() -> None:
     config_hash = 0x12345678
     build_time = 1700000000
     build_time_str = "2023-11-14 22:13:20 +0000"
+    comment = "Test comment"
 
-    result = generate_build_info_data_h(config_hash, build_time, build_time_str)
+    result = generate_build_info_data_h(
+        config_hash, build_time, build_time_str, comment
+    )
 
     assert "#pragma once" in result
     assert "#define ESPHOME_CONFIG_HASH 0x12345678U" in result
     assert "#define ESPHOME_BUILD_TIME 1700000000" in result
+    assert "#define ESPHOME_COMMENT_SIZE 13" in result  # len("Test comment") + 1
     assert 'ESPHOME_BUILD_TIME_STR[] = "2023-11-14 22:13:20 +0000"' in result
+    assert 'ESPHOME_COMMENT_STR[] = "Test comment"' in result
 
 
 def test_generate_build_info_data_h_esp8266_progmem() -> None:
     """Test generate_build_info_data_h includes PROGMEM for ESP8266."""
-    result = generate_build_info_data_h(0xABCDEF01, 1700000000, "test")
+    result = generate_build_info_data_h(0xABCDEF01, 1700000000, "test", "comment")
 
     # Should have ESP8266 PROGMEM conditional
     assert "#ifdef USE_ESP8266" in result
     assert "#include <pgmspace.h>" in result
     assert "PROGMEM" in result
+    # Both build time and comment should have PROGMEM versions
+    assert 'ESPHOME_BUILD_TIME_STR[] PROGMEM = "test"' in result
+    assert 'ESPHOME_COMMENT_STR[] PROGMEM = "comment"' in result
 
 
 def test_generate_build_info_data_h_hash_formatting() -> None:
     """Test generate_build_info_data_h formats hash with leading zeros."""
     # Test with small hash value that needs leading zeros
-    result = generate_build_info_data_h(0x00000001, 0, "test")
+    result = generate_build_info_data_h(0x00000001, 0, "test", "")
     assert "#define ESPHOME_CONFIG_HASH 0x00000001U" in result
 
     # Test with larger hash value
-    result = generate_build_info_data_h(0xFFFFFFFF, 0, "test")
+    result = generate_build_info_data_h(0xFFFFFFFF, 0, "test", "")
     assert "#define ESPHOME_CONFIG_HASH 0xffffffffU" in result
 
 
+def test_generate_build_info_data_h_comment_escaping() -> None:
+    """Test generate_build_info_data_h properly escapes special characters in comment."""
+    # Test backslash escaping
+    result = generate_build_info_data_h(0, 0, "test", "backslash\\here")
+    assert 'ESPHOME_COMMENT_STR[] = "backslash\\\\here"' in result
+
+    # Test quote escaping
+    result = generate_build_info_data_h(0, 0, "test", 'has "quotes"')
+    assert 'ESPHOME_COMMENT_STR[] = "has \\"quotes\\""' in result
+
+    # Test newline escaping
+    result = generate_build_info_data_h(0, 0, "test", "line1\nline2")
+    assert 'ESPHOME_COMMENT_STR[] = "line1\\nline2"' in result
+
+
+def test_generate_build_info_data_h_empty_comment() -> None:
+    """Test generate_build_info_data_h handles empty comment."""
+    result = generate_build_info_data_h(0, 0, "test", "")
+
+    assert "#define ESPHOME_COMMENT_SIZE 1" in result  # Just null terminator
+    assert 'ESPHOME_COMMENT_STR[] = ""' in result
+
+
 @patch("esphome.writer.CORE")
 @patch("esphome.writer.iter_components")
 @patch("esphome.writer.walk_files")
@@ -1445,6 +1476,7 @@ def test_copy_src_tree_writes_build_info_files(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF
+    mock_core.comment = "Test comment"
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = [("core", mock_component)]
@@ -1466,6 +1498,8 @@ def test_copy_src_tree_writes_build_info_files(
     assert "#define ESPHOME_CONFIG_HASH 0xdeadbeefU" in build_info_h_content
     assert "#define ESPHOME_BUILD_TIME" in build_info_h_content
     assert "ESPHOME_BUILD_TIME_STR" in build_info_h_content
+    assert "#define ESPHOME_COMMENT_SIZE" in build_info_h_content
+    assert "ESPHOME_COMMENT_STR" in build_info_h_content
 
     # Verify build_info.json was written
     build_info_json_path = build_path / "build_info.json"
@@ -1517,6 +1551,7 @@ def test_copy_src_tree_detects_config_hash_change(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF  # Different from existing
+    mock_core.comment = ""
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = []
@@ -1578,6 +1613,7 @@ def test_copy_src_tree_detects_version_change(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF
+    mock_core.comment = ""
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = []
@@ -1627,6 +1663,7 @@ def test_copy_src_tree_handles_invalid_build_info_json(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF
+    mock_core.comment = ""
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = []
@@ -1700,6 +1737,7 @@ def test_copy_src_tree_build_info_timestamp_behavior(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF
+    mock_core.comment = ""
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = [("test", mock_component)]
@@ -1794,6 +1832,7 @@ def test_copy_src_tree_detects_removed_source_file(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF
+    mock_core.comment = ""
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = []  # No components = file should be removed
@@ -1855,6 +1894,7 @@ def test_copy_src_tree_ignores_removed_generated_file(
     mock_core.relative_build_path.side_effect = lambda *args: build_path.joinpath(*args)
     mock_core.defines = []
     mock_core.config_hash = 0xDEADBEEF
+    mock_core.comment = ""
     mock_core.target_platform = "test_platform"
     mock_core.config = {}
     mock_iter_components.return_value = []